Chemoattractant receptors on phagocytic cells

Area of Science:

• Immunology
• Cell Biology
• Pharmacology

Background:

• Leukocyte chemoattractant receptors initiate diverse cellular responses like motility, secretion, and respiratory burst.
• Distinct dose-dependencies suggest differential regulation of motility versus secretory/respiratory burst functions.
• Oligopeptide chemoattractant receptor affinity is heterogeneous and dynamically regulated.

Purpose of the Study:

• To investigate the differential regulation of chemoattractant receptor-mediated functions in leukocytes.
• To elucidate the role of receptor affinity states and guanine nucleotide regulation in cellular signaling.
• To explore the involvement of transmethylation and protein kinase C in chemoattractant responses.

Main Methods:

• Direct binding studies to identify receptor affinity states.
• Pharmacological manipulation of chemoattractant receptor signaling.
• Investigation of transmethylation reactions and protein kinase C activation.

Main Results:

• Motility functions are triggered by lower chemoattractant doses than secretory/respiratory burst activities.
• Low agonist doses induce interconversion between low- and high-affinity receptor states modulated by guanine nucleotides.
• High agonist doses lead to guanine nucleotide-insensitive, internalized high-affinity receptors, desensitization, secretion, and respiratory burst.

Conclusions:

• Chemoattractant receptor functions are differentially regulated, allowing for targeted drug modification.
• Guanine nucleotide-dependent and -independent receptor states play critical roles in leukocyte activation.
• Transmethylation and protein kinase C are essential for chemoattractant-induced arachidonate release and stimulus-response coupling.